The processes for producing monofilaments from thermoplastic polymers are known in principle and are described, for example, in Handbuch der Kunststofftechnik II, C Hauser Publishers, Munich 1986, pp. 295-319.
It is further known that the notched bar impact strength of moulded bodies of thermoplastic polymers can be improved by the addition of polyethylene/polypropylene rubber. In known manner the polymer mixtures of thermoplastic polymers and modified polyethylene/polypropylene rubber are granulated and compounded on double-shaft extruders and processed by injection moulding.
To date, few suitable polymer mixtures have become known for the manufacture of monofilaments for technical purposes, such as further processing into press felts for the paper industry, which must in particular have high mechanical strength with respect to abrasion. From US patent specification 5 169 711 it is known that the abrasion resistance of monofilaments of polyethylene terephthalate (PET) can be increased by the addition of thermoplastic polyurethane (TPU).
Monofilaments of polymer mixtures of polyamide, polyphenylene ether and a functionalized elastomer are also known for the manufacture of press felts (see international patent application WO 93/1325 for example).
The abrasion resistance of the monofilaments and hence of the technical fabrics that can be produced from them is improved by the above-mentioned known raw material modifications to only an inadequate extent, and in addition the strength of the monofilaments is reduced.